In my co-pending U.S. application Ser. No. 631,847 filed Nov. 13, 1975 for "Micropipette Filter Tips" there is disclosed a filter for use with the disposable plastic tips of micropipettes. The filter is of porous plastic or metal and is designed to engage the tip while the liquid is being sampled and simultaneously filtered. Thereafter the filter may be removed and the filtered liquid discharged. In one of the embodiments disclosed in such application, the filter is shown in the form of a sphere having a conical recess for frictionally engaging the tip of the micropipette.
Filters of the type covered by the aforesaid pending application are useful laboratory tools. However, one potential disadvantage arises from the fact that the filter itself provides the frictional engagement retaining it on the tip. This means that if a number of tips are employed having different sizes and shapes, there must be an equally large selection of filters, even though the filtering material may be the same. Furthermore, if a selection of filter materials is desired, it would be necessary to make the filters of each material in a sufficiently large variety to fit all the various tips with which they are apt to be used. Accordingly, it is a primary object of the present invention to provide filter assemblies comprising a body member having a size and shape to engage a specific tip and a standardized filter insert which may be interchangeably associated with all such holders. Other objects, features, and advantages will become apparent from the following description and appended claims.